1. Field of the Invention
The present invention relates to an original reading apparatus that reads an image from an original.
2. Description of the Related Art
Generally, an image reading apparatus that reads a color image from an original is provided with three line sensors. Each line sensor reads one of pieces of color information corresponding R (red), G (green), and B (blue). A color filter for separating light and an imaging lens for imaging light are provided on an optical path from an original to each line sensor. On an imaging lens or an original stage glass, chromatic aberration depending on the wavelength of light is generated. Accordingly, even when an image at the same position on an original is read by the line sensors, the positions of images projected on the line sensors slightly differ from each other, and this difference appears as so-called color misalignment. Japanese Patent Laid-Open No. 2006-340232 discloses a technique that reads thin lines to detect color misalignment amounts, obtains R and G color misalignment amounts as the numbers of pixels using B as a reference, and corrects the misalignment through image processing according to the misalignment amounts.